Pure spin photocurrents in low-dimensional structures
S. A. Tarasenko , E. L. Ivchenko
A. F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St.Petersburg, Russia
PACS: 72.25.-b, 73.63.Hs, 78.67.De
Abstract
As is well known the absorption of circularly polarized
light in semiconductors results in optical orientation of electron
spins and helicity-dependent electric photocurrent, and the
absorption of linearly polarized light is accompanied by optical
alignment of electron momenta. Here we show that the absorption of
unpolarized light leads to generation of a pure spin current,
although both the average electron spin and electric current
vanish. We demonstrate this for direct interband and intersubband
as well as indirect intraband (Drude-like) optical transitions in
semiconductor quantum wells.